Something is bent somewhere. Stand the lens on its front on a smooth flat surface. Lay a rigid straight edge across the center of the lens rear. Using a caliper or fine graduation ruler measure from the straight edge to the work surface on both sides of the lens. Rotate the straight edge 30° and remeasure, repeat until you have a measurement for the full circumference of the lens. A thin metal ruler on edge makes a good straight edge. Expect a .050 to .1 inch variance minimum to cause the problem. If all measurements are equal or less than .010 variance then measure the diameter of the lock ring on the lens every 30° to find if a bent section exists there. 30° is 5 minutes on a clock/watch face. Post a picture of the lens mount side of the lens. The shutter click and dial suggest its time to have a CLA done on the body.